Method for increasing subterranean formation permeability



3,270,808 METHOD FOR INCREASING SUBTERRANEAN FORMATION PERMEABILITY Robert R. Harvey, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed Feb. 25, 1963, Ser. No. 260,864 6 Claims. (Cl. 166-9) This invention relates to a method for increasing the water permeability of a subterranean formation. In one aspect the invention is related to the art of recovering hydrocarbon from underground formations. More speci=fically it relates to an improved w agg rflood pgg cgdpge.

The use of Water injection in secondary i e'covery of petroleum is wide spread. In a waterflood operation, water is injected through one or more input wells causing the oil to be displaced from the formation surrounding the input wells. This oil travels at the head of the waterflood front from the formations surrounding the input to the output well from which the oil is produced in the usual manner. In such secondary recovery operations it is necescary that large volumes of water be injected into the oil bearing formation at reasonable heads. In the primary production of oil it is also sometimes necessary to dispose of large quantities of brine produced with the oil. In disposing of such brine by injection into a subterranean formation it is again necessary that the input well handle large volumes of fluid at reasonable pressures.

Mechanical clean-out, acid treatment and solvents have been used with varying degrees of success for increasing the input of flood water and brine into the formation. The first two of these methods are generally effective but the labor and cost involved and the loss of input time in the Well while it is being serviced make these methods expensive. Chemical additives such as sodium carbonate, surface active agents and the like have been added but these additives have not been used extensively primarily due to difliculty experienced in selecting the proper additive for a specific formation.

It is an object of the invention to provide an improved method for increasing the water permeability of a subterranean formation.

It is another object of the invention to provide an improved method for the recovery of hydrocarbon oil from underground formations. It is yet another object of the invention to provide an improved method for water flooding an oil bearing formation.

These and other objects of the invention will be readily apparent to those skilled in the art from a reading of the accompanying disclosures and claims.

These objects are broadly accomplished by the employment of an additive selected from the groups consisting where R and R are selected from the group consisting of H, OH, R, R OH, COOH and R COOH, at least one R being OH,

R is an alkyl group having 1 to 4 carbon atoms per molecule, and

SEARCH ESQ-M 3,270,808 Patented Sept. 6, 1966 p CC R is an alkylene group having 1 to 3 carbon atoms per molecule;

where R, is selected from the group consisting of H, OH, R, R OH, COOH, and R COOH, at least two R s being OH and said structure being oxidizable to a quinone;

(C) flavotannins;

(D) gallotannins;

(E) mixed tannins;

(F) quinhydrone;

(G) p-benzoquinone;

(H) l-naphthol;

(I) 1,3-naphthalenediol;

(J) phloroglucinol and Z-methylphlorOglucinol, and (K) mixtures thereof.

Although a wide variety of compounds are suitable for increasing the water wettability of the oil formation, the following compounds are included in the above identified groups.

Group A.--Pyrocatechol, pyrogallol, gallic acid, hydroquinone, 1,2,4-benzenetriol, 2,5-xylohydroquinone, 3-butylpyrocatechol, 4-isopropylpyrocatechol, 2,3-dihydroxybenzyl alcohol, 3 (2,5-dihydroxy-m-tolyl)-1-propanol, (2,5-dihydroxyphenyl)acetic acid, 4-(3,4-dihydroxyphenyl) butyric acid and the like.

Group B.l,7-naphthalenediol, 2,3 naphthalenediol, 1,5-naphthalenediol, 2,6-naphthalenediol, 2 methyl-1,7- naphthalenediol, 1-butyl-2,3-naphthalenediol, 1,2,5-naphthalenetriol, l-i-sopropyl-2,6-naphthalenediol, 4,6 dihydroxy-3-methyl-l-naphthalenemethanol, 6 ,7-dihydroxy-2- naphthalenepropanol, 4,8 dihydroxy-Z-naphthaleneacetic acid, 3,7-dihydroxy-alpha-met hyl-1-naphthalenepropionic acid and the like.

Group C.These flavotannins may be synthetic or naturally occurring such as those found in plants as gambier, catechu, quebracho, tizerah, urunday, wattle, mangrove, spruce, hemlock, larch, willow, avaram, Chinese rhubanb, guarana, mahogany, birch, wild cherry, horse chestnut, hotentot fig, iron wood, and teak. A particularly preferred flavotannin is quebracho which is obtained from the dried wood or bark, or dried extract of such wood or bark, of the aspidosperma quebracho branco or the quebracho lorentzi tree. Quebracho is readily available commercially.

Group D.Tl1ese gallotannins may be synthetic or naturally occurring such as sumac tannin and the tannins of valonia oa-k gall, tea, tara or' carabin, valonia fruit cups and beard, myrabolarn nuts, dividivi pods, algarobil-la pods, oak wood, bark, and leaves, chestnut wood, bark,

and leaves, cloves, dhawa, guarana, mangue talkaout,

pomegranate, water lily, horn'beam, bistont, guayacan, and cascalote.

Group E.The soacalled mixed tannins are also applicable such as bablah, badan, Cyprus sumac, filao, maletto, and wandoo.

Many formations are preferentially oil wet due to the presence of naturally occurring surface active agents in the reservoir fluids, these agents being absorbed on the solid surface of formations. Minerals in other formations may exhibit a preferential wettability to the crude oil. Greatly increased oil recovery in a waterfl-ooding operation can be obtained by causing a formation to become preferentially wet by the flood water rather than by the formation crude oil. I have discovered that this reversal of preferential wettability can be caused by the addition to the flooding water of at least one of the above described additives.

The additive of this invention to the flood water is present in the flood water in an amount in the range of 0.1 to 10, preferably 0.5 to weight percent, although it is only necessary that an amount of additive be present suflioient to increase the permeability or water wettability of the format-ion.

The non-quinone additives of this invention other than the quinones and additives H, I and J are oxidizable to a quinoid structure. Quinones, as employed herein, refer to dioxo derivatives of dihydroaromatic systems, the oxygen atoms occupying positions which are ortho or para (or their equivalents in polycyclic compounds) to each other. A most generally applicable procedure for preparing a qu-inone is to start with a phenol or an amine, introduce either a hydroxyl or an amino group in an ortho or para position, and oxidize the intermediate in acid solution.

It is preferred that the pH of the waterflood containing the additive be controlled or adjusted to a range of 3 to 14, preferably 5 to 12, more preferably 7 to 12. Best results are generally attained when the pH of the flood water containing the additive is in the range of 9 to 12.

The pH of the solution may be adjusted by the addition of a base, e.g., an alkali metal hydroxide such as sodium hydroxide, or ammonium hydroxide or an alkali metal carbonate if the carbonate does not react with the mineral constituents Otf the reservoir.

It is sometimes helpful to include a reducing agent which will aid in solubilizing and maintaining the additive in solution, e.g., an alkali metal sulfite such as sodium sulfite, sodium bisulfite, sodium hydrosulfite or ammonium sulfite or sufur dioxide or the like. Although the mechanism is unknown it is believed that the reducing agent also assists in the inhibition of the polymerization of some of the polymerizable additives.

The reducing agent is employable in an amount in the range of 2 to 50 weight percent, preferably 5 to 20 weight percent, based on the additive.

In conjunction with the flood water containing the additive, it is also within the scope of the invention to use a solvent flood in advance of the waterflood. Steam or hot water is also employable. It is also in the scope of the invention to include a detergent or a wetting agent along with the additive of this invention. In some formations it may be necessary [for the additive to be included only in the initial portion of the flood water so as to increase the permeability of an area adjacent the input well.

The word water as used in this specification and the appended claims is taken to include the various aqueous materials which are suitable for injection into an oil containing formation in secondary recovery waterflood proc esses and further includes aqueous solutions which may conveniently be disposed of by injection into a subterranean formation, such as saline waters.

Wettability, as referred to herein, refers to the Amott wettability measurement method 1 as modified by the inventor. A fresh core is prepared by canning the core in formation oil. When the cores are received in the laboratory, permeability plugs, 1.88 cm. in diameter by 3.5 cm. (1%") in length are drilled from the core parallel to the bedding plane. The drilling with a diamond bit, and the cutting oif of the ends with a diamond saw are done with either the formation oil or formation water as a cutting fluid.

(1) The sample is placed in a 4 inch centrifuge tube With 1 inch of sand under the sample and /2 inch of sand above the sample. Formation water is added to saturate 1 Earl Amott. Observations Relating to the Wettability of Porous Rock, Trans AIME, 216 (1959).

the sand to /2 inch from the top of the tube. The tube is capped and centrifuged at 33,000 gravities for 1 hour at 20 C. The sample core is then removed, washed with the water phase, placed in another centrifuge tube as above but with formation oil instead of formation water and recentrifuged as above. The core is removed, washed with oil phase, rolled on an oil dampened paper towel to remove excess oil and weighed immediately in a weighing bottle. This is Weight A.

(2) The core is submerged in water phase for 24 hours, removed, Washed with water phase, rolled on paper to remove excess water and weighed. This is weight B.

(3) Compute I =B-A.

(4) The core is centrifuged as before under water phase, removed, washed with water phase, rolled and weighed. This is weight C.

(5) Compute T =C-A and (6) Step 2 is repeated substituting oil for water. This is weight D.

(7) Compute I =C-D.

(8) Repeat step 4 using oil instead of water. This is weight E.

(9) Compute T =C-E ow Z OWZ (10) Compute wettability index W=R Rowy The wettability index of a completely oil wet sample is thus 1 whereas that of a completely water wet sample is +1.

The invention is best illustrated by the following examples.

EXAMPLE I Table I Additive W0 (Avg) wfinal AW (Avg) llyrocatechol -0. 63 0. 08 +0. 55 p-Benzoquinone 0. 72 0. 22 +0. 50 Hydroquinone" 0. 78 0. 23 +0. 55 Qumhydrone -O. 72 0. 39 +0. 33

The above data prove the effectiveness of the additive for increasing water wettability of the formation.

EXAMPLE II The elfectiveness of quebracho at different pH levels and in the presence of NaHSO was determined by dissolving 17.1 gms. of quebracho in 3 liters of NBU brine /2% $01.). This solution was divided into two 1500 ml. portions and 0.86 gm. of NaHSO was added to one portion (10% of weight of quebracho). Each of the portions was divided into 3 parts and NaOH added to adjust the pH to 5, 7 and 9 in each of the following two sets.

at a lower pH and in the presence of NaHSO EXAMPLE H1 The effectiveness of quebracho at higher pH values and at higher concentrations was found to be as follows.

6 In addition to the above, centrifuge tests with Burbank crude and fresh Burbank cores showed that the addition of 1 weight percent of bulk quebracho to simulated Burbank brine flood water reduces the average unre- Table III Quebmcho/distllled water N aHSOa/distilled H50 pH l W 100 gmsJl 10 0. 62 30 grns./1 11 0.48

EXAMPLE IV Runs made on equimolar mixtures of p-benzoquinone and pyrocatechol at different total molarities and a pH of 10 produced wettability changes as follows.

Table IV Molarity W0 W1 A W This indicates that mixtures of these additives are equally effective at different levels of concentration.

EXAMPLE V A quinone forming naphthalenediol was compared to a non-quinone forming n-aphthalenediol at a pH of 10 with changes in wett-ability as follows.

The effectiveness of quebracho at different concentrations for increasing the oil recovery was as follows.

Table VI Quebracho, weight percent Additional Percent Im- A W oil, BPAF 1 provement Barrels per acre foot, calculated as discussed in Uren, "Petroleum Production Engineering, Oil Field Exploitation, McGraw-Hlll Book Company, New York (9163), page 85.

covered residual oil content from 262 to 161 BPAF.

EXAMPLE VII A number of additives were compared on Burbank cores as described in Example I at a concentration of 10 2 weight percent additive and with an adjusted pH of 9. The results are tabulated as follows. W was about -O.50 in all samples.

Wt AW Table VII Additive W: AW

Resorcinol 0.44 +0.06 0 PyrocatechoL +0.01 +0.51 Phloroglucinol- 0. 38 +0. 12 Pyrogallol +0.02 +0.52 Hydroquinone- 0. 05 +0. 1,7-naphthalenedio 0. 04 +0. 46 2,3-naphthalenedioL 0 +0. 2,6-naphthalenedi0L. 0. 10 +0. 40 40 Quinhydrone 0.07 +0.43 Gallic acid 0.04 +0.46 1,5-naphthalened 0. 46 +0.04 2,7-naphtha1enedioL. 0. 48 +0. 02 1,8-anthradiol- 0. 62 0. 12 0.42 +0.08 0. 27 +0. 23 -0. 18 +0.32 0. 58 0.08 -0 08 +0.42 0. 52 0.02 0.49 +0.01 2,5-dihydroxy-p-benzoquinone. 0. 60 0. 1O o-Phenylphenol 0. 48 +0. 02 1,2-naphthoquinone. 0. 56 0. 06 50 Anthraquinone 0.62 0. 12 Trihydroxy-p-benzoquinone. -0. 62 0. 12 1,5-dihydroxyanthraquinone- 0. 51 0. 01 1,S-dihydroxyanthraquinone.. 0. 47 +0. 03 1,2,3-trihydroxyanthraquinone 0. 67 0. l7 1,2,4-trihydroxyanthraquinone 0. 65 0. 15 1,2,7-trihydroxyanthraquinone 0. 53 0. 03 1,2,5,8-tetrahydroxyanthraquinone 0. 41 +0. 09 55 2methylph1oroglucinol 0. 32 +0.18 Tetramethyl-p-benzoquinone 0. 53 0. 03

These examples indicate that a large number of additives which would appear to be chemically similar to those claimed are either inoperable or so ineffective as to be of little value commercially.

While certain examples, structures, composition and process steps have been described for purposes of illustration, the invention is not limited to these. Variation and modification within the scope of the disclosure and the claims can readily be effected by those skilled in the art.

I claim:

1. A process for the recovery of oil from a subterranean formation comprising injecting flood water into said formation through an input well, displacing oil in said formation, directing the displaced oil toward an output well and recovering said displaced oil from said output well, said flood water having present therein a oompound selected from the group consisting of quebracho,

pyrocatechol and hydroquinone in an amount sufiicient to increase the water permeability of said formation.

2. The process of claim 1 wherein said amount is in the range of 0.01 to 10 weight percent based on flood water.

3. The process of claim 1 wherein said additive comprises quebracho.

4. The process of claim 1 wherein said additive oomprises pyrocatechol.

5. The process of claim 1 wherein said additive comprises hydroquinone.

6. A process for the recovery of oil from a subterranean formation comprising injecting flood water into said formation through an input well, displacing oil in said formation, directing the displaced oil toward a producing well and recovering said displacedgiljggng ggi d produgigg vyeg w herein the formation is rendered preferentially oil-wet by injecting quebrachoatannin with,said flood water, said quebracho tannin being present in an amount in the range of 0.5 to 5.0 weight percent based on flood water and said mixture of quebracho tannin and floodwater having a pH in the range of 7 to 14.

References Cited by the Examiner UNITED STATES PATENTS 2,246,726 6/1941 Garrison 2528.55 2,738,325 3/1956 Rydell 1669 2,831,022 4/1958 Van Blaricom 252-8.5 

1. A PROCESS FOR THE RECOVERY OF OIL FROM A SUBTERRANEAN FORMATION COMPRISING INJECTING FLOOD WATER INTO SAID FORMATION THROUGH AN INPUT WELL, DISPLACING OIL IN SAID FORMATION, DIRECTING THE DISPLACED OIL TOWARD AN OUTPUT WELL AND RECOVERING SAID DISPLACED OIL FROM SAID OUTPUT WELL, SAID FLOOD WATER HAVING PRESENT THEREIN A COMPOUND SELECTED FROM THE GROUP CONSISTING OF QUEBRACHO, PYROCATECHOL AND HYDROQUINONE IN AN AMOUNT SUFFICIENT TO INCREASE THE WATER PERMEABILITY OF SAID FORMATION. 